This invention relates to internal combustion engine. More particularly, this invention relates to starting systems for engines having electronic governors.
It is desirable to use electronic governors in small internal combustion engines to keep the engine running near a set or governed speed. Since electronic governors require a source of electrical power to operate, a battery has typically been used to power the electronic governor. The electronic governor typically powers a stepper motor which in turn changes the throttle position through a linkage. However, a battery is expensive and thus greatly increases the cost of a device that is powered by the small internal combustion engine, such as a lawnmower, snowblower, generator or the like.
Several attempts have been made to eliminate the battery and to use regulated power generated by an alternator to power the electronic governor. None of these devices has been successfully commercialized, however, due to certain problems inherent in their designs.
One major problem with such designs is that they do not allow the engine to have a Wide Open Throttle (WOT) at engine starting speeds since the alternator is generating insufficient power at such speeds to enable the governor to open the throttle to the Wide Open Throttle or "Start" position.
Since electronic governors typically have a return spring which moves the throttle plate to the idle (closed) position when the engine is shut off, an electronic governor that is powered by an alternator must be able to start at closed throttle. However, small internal combustion engines are typically designed to start at the Wide Open Throttle position. Thus, either a battery is required to place the throttle in the WOT position, or the operator must manually move a lever to open the throttle to the WOT position before engine starting.
Both of these proposed solutions are unsatisfactory. The use of a battery, as explained above, greatly increases the cost of the device. The requirement that the operator manually open the throttle to the WOT position is also unsatisfactory since the engine will not start if the operator forgets to open the throttle. Also, the manual system could be unsafe if the operator fails to thereafter move the lever to a running position from the WOT position. In that event, the lawnmower would continue to run at Wide Open Throttle, potentially damaging the engine components.
Another possible solution could be to have the engine run at Wide Open Throttle at engine running speeds. When the engine is shut off and subsequently restarted, the throttle would already be in the WOT position. However, this solution is also unsatisfactory since running the engine at the WOT position for an extended period will cause premature engine wear and may be unsafe.